On the right side of this page in the "my favorite websites" section you'll see a link to:
The Athletic Trainers Society of New Jersey
Since it's inception I've always believed it's been a superior website that was the brainchild of Mike Goldenberg ATC- A guy that has always been on the cutting edge of this stuff.
Great information for athletes, coaches, parents, and fellow athletic trainers. Be sure to take a look at the new concussion section.